Software Vault: The Diamond Collection/The Diamond Collection (Software Vault)(Digital Impact).ISO/cdr16/tc15_089.zip/TC15-089.TXT

Text File | 1995-03-12 | 23KB | 628 lines

TELECOM Digest     Thu, 9 Feb 95 12:09:00 CST    Volume 15 : Issue 89

Inside This Issue:                         Editor: Patrick A. Townson

    Re: Emergency Cellular Phone (Matthew Dukleth)
    Re: 28.8k bps Modem (James Carlson)
    Re: 28.8k bps Modem (Stephen Palm)
    Re: 28.8k bps Modem (John Combs)
    Re: 28.8k bps Modem (Ken Culbert)
    Re: 28.8k bps Modem (John Lundgren)
    Re: Chicago 630 Plan - Such As It Is (Kevin Kadow)
    Re: POCSAG to be Upgraded to APOC (Matthew Cheng)
    Re: Ten Digit Dialing (Carl Moore)
    Re: Unit to "Speak" CLID (Mike Roche)
    Re: Clock Slips Again (Martin McCormick)
    Looking for Hands on Networking Experience (Al Gharakhanian)
    Re: Who Belongs to 10732 Five-Digit Access Code? (Peter M. Weiss)
    Re: GTE PCS/Global Roam (John Mark)
    Re: Cellular Fraud: How Much of it is Real Money? (David Buerger)

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----------------------------------------------------------------------

From: [e-mail] (Matthew Dukleth)
Subject: Re: Emergency Cellular Phone
Date: 9 Feb 1995 17:50:51 GMT
Organization: Netcom


Yes, such a product is being developed.  Here is the information I
have:

1. Beta tests of the phone have been underway for about two months,
and
will be completed, sucessfully, soon.

2. Service is contemplated in about three months.

3. The phone will have alkaline batteries, and a cigarette adaptor, so
it can be stored in a car glove box for an extended period of time,
and
still work.

4. And, the cost will probably not be zero, but will be very low
compared to current cellular service.  Also, the per minute charge
will
include long distance, as well as cellular airtime, for a fixed price -
-
to anywhere in the United States.

If anyone would like more information, please contact either:


Beth Walsh, The National Dispatch Center, [e-mail]
Jack Nargundkar, The National Dispatch Center,
[e-mail]

------------------------------

From: [e-mail] (James Carlson)
Subject: Re: 28.8k bps Modem
Date: 9 Feb 1995 18:02:04 GMT
Organization: Xylogics Incorporated
Reply-To: [e-mail]


In article <[e-mail]>, Paul Robinson <[e-mail]>
writes:

>> 1.  Is the bps across the twisted pair wire actually running at
28.8 or
>> 14.4 when 28.8 is invoked? Or is it just data compression?

> The raw data rate for a modem will be from 110 to 28,800 baud (or
> 14,400 baud) depending on what the other side agrees on.  The rate
> will be the lowest of whatever the two modems agree on. If you call
up
> a service that has only 14.4 modems, or 9600 baud modems, or even
> 2400, you will only get 14.4 or 9600 or 2400 even though your modem
> can do more.  If both modems are 28.8 and both have their highest
> speed enabled, you should see 28,800 baud before any compression
> occurs.

> The data is not sent at 28,800 bits per second, however.  Typically
> the modem will divide up the telephone line into six or more
channels,
> and run each channel at 2400 to 4800 bits per second.  By
multiplexing
> six channels at 2400 baud, you get 14,400 baud, etc.

One or two minor nits: the data are sent at 28,800 bits per second,
but not
at 28,800 baud.  The difference is that a bit is a binary digit (a
single one
or zero) while a baud is a signal-element-per-second.  The signal
elements
sent by the modem each represent several bits (actually, with
28.8Kbps, it's
a variable amount), thus with about 3200 baud and 9 bits per baud you
get
28,800.

This is a synchronous data rate, so async framing conversion data and
data compression run on top of this 28.8Kbps pipe.

Unfortunately, too many sales and marketing folks have confused the
bps
versus baud issue, and the terms have lost much of their original
meaning.  The language is all the poorer for this.


James Carlson <[e-mail]>            Tel:  [phone]
Annex Software Support / Xylogics, Inc.               [phone]
53 Third Avenue / Burlington MA  01803-4491     Fax:  [phone]

------------------------------

From: [e-mail] (Stephen [kiwin] PALM)
Subject: Re: 28.8k bps Modem
Organization: Rockwell International Japan, JEDC
Date: Thu, 9 Feb 1995 12:20:03 GMT


Steve Midgley <[e-mail]> wrote:

> With sheepish apologies to the moderator and readers, I amend my
> previous post. I must have sleeping sitting down :-)

> V.32 is not the protocol spec for 14.4 modems. It's V.42.
Apologies,
 apologies.

Actually, you still have it wrong.

V.32bis is where the 14.4kbps full duplex modulation is defined.

V.42 is an error correction procedure (than can be used with several
different modulations including V.32bis).

Paul Robinson <[e-mail]> wrote:

> The raw data rate for a modem will be from 110 to 28,800 baud (or
> 14,400 baud) depending on what the other side agrees on.

Actually, it would be 110 to 28,800 bits ber second.

A V.34 28,800 modem can use one of 6 baud (or symbol) rates at a time:
  2400, 2743, 2800, 3000, 3200, 3249

> The data is not sent at 28,800 bits per second, however.
> Typically the modem will divide up the telephone line into six
> or more channels, and run each channel at 2400 to 4800 bits per
> second.  By multiplexing six channels at 2400 baud, you get
> 14,400 baud, etc.

This is incorrect for V.34 (28,800) modems.  A V.34 modem only uses a
single "channel".  During negotiation, the line is characterized by a
process refered to as "line probing". Based on that information, one
of the 6 symbol rates listed above is selected.  To achieve multiple
bits per baud, Trellis Coding is used.

[stuff deleted... now discussing FAX]

> There are two speeds for transmissions.  First, when the connection
is
> being set up, each side will send an identifier sequence.  I call it
> the "answerback" after the similar sequence sent by a telex machine.
> This identifier sequence is called a TTI or CSI.  One of these will
> typically appear in the log that the fax machine prints after 20-40
> transmissions indicating the identifying machine.  The other is the
> telephone number or other identifier that appears in the display
> window.  The two items may be different.  This information is
> transmitted by each machine at 300 baud, which is okay since it is
> typically no more than 60 characters for each side.

This 300 baud (which is also 300 bits per second in this case)
modulation
is the V.21 high channel.  Several other pieces of information (such
as machine capabilities, page width, etc) are also transfered in a
protocol defined in T.30.

> The sending machine then increases its speed and the transmission
> takes place in the equivalent of "half duplex" mode, except that the
> recipient machine typically acknowledges the end of each page and
end
> of transmission.

Image transmission is done by V.17, V.29, or V.27ter which are all
Half Duplex only modulations.

> The ITU standard for fax machine transmissions supports 4800, 9600,
> 12000, and 14400 baud, but typically a fax machine that does
printing
> will do 9600 tops, and can be downgraded to 4800 if line conditions
> are bad.

The bottom speed is 2400 bits per second for really crummy lines.

> 12000 and 14400 are typically for fax modems in computers.

But many expensive FAX machines support 14,400 (V.17) too.  And you
should see a lot more "cheaper" FAX machines supporting V.17 in the
coming year.


Regards,

Stephen [kiwin] Palm                        TEL (Voice mail): +81-3-
5371-1564
Rockwell - Digital Communications Division                   COMNET:
930-1564
Japan Engineering Design Center      (JST=PST+17hours)   FAX: +81-3-
5371-1507
  [e-mail]   [e-mail]   [e-mail]
[e-mail]

------------------------------

Date: Wed, 8 Feb 1995 23:41:00 EST
From: Testmark Laboratories <[e-mail]>
Subject: Re: 28.8kbps modem


I connect to MCImail late at night via a 14.4kbps modem, with V.42bis
compression, which is theoretically 4:1.  I regularly get throughputs
of 4200cps or better, which shows a compression ratio of 3:1.  I
recently saw a review of 28.8kbps modems in {InfoWorld}, and they saw
true 4:1 bit compression on modems under "ideal" circumstances, i.e.,
very high- powered PCs, using V.34 modems with V.42bis compression on
parallel ports, or on specially-buffered serial ports.  This is not
what occurs in the "real-world" because the local PC, or the host/main-
frame, is often the slowdown, not the modems themselves.


John Combs, Project Engineer, TestMark Laboratories,
[e-mail]

------------------------------

Date: Thu, 09 Feb 1995 12:35:10 GMT
From: [e-mail] (Ken Culbert)
Subject: Re: 28.8k bps Modem
Organization: Funk Software, Inc.


In article <[e-mail]>, [e-mail] (Steve
Midgley) wrote:

> With sheepish apologies to the moderator and readers, I amend my
> previous post. I must have sleeping sitting down :-)

> V.32 is not the protocol spec for 14.4 modems. It's V.42.
Apologies,
> apologies.

Wrong again.  V.32bis is the modulation protocol spec for 14.4 kbaud;
v.42 is the reliability spec; v.42bis is the compression standard;
v.34 is the modulation protocol for 28.8 kbaud.

Not too confusing, eh? ;)


Ken Culbert           [e-mail]
Funk Software, Inc.   http://www.funk.com
222 Third Street      voice: 617 497-6339
Cambridge, MA 02142   fax:   [phone]

------------------------------

From: [e-mail] (John Lundgren)
Subject: Re: 28.8k bps Modem
Date: 9 Feb 1995 10:39:49 GMT
Organization: Pacific Bell Knowledge Network


David Sacerdote ([e-mail]) wrote:

> If you purchased a modem which supports the v.34 standard AND are
> using a computer to modem communications speed which is faster than
> 28800bps it will actually travel across the wire at 28800bps,
assuming
> no line noise, no error correction, and no compression.  I am also
> assuming that you are connecting to another modem which supports the
> V.34 standard, or whatever proprietary standard your modem supports.

What is 'it' in 'it will travel..' above.  I think that the above
isn't telling much of the story.  The link between modems may be at
28,800 BPS, but the bytes are being transmitted as octets,
synchronously.  They are not 10 bit asynchronous bytes as they are
between the PC and modem.  Also, there are other things done between
the two modems, such as error detection and correction, and
compression.  So what is going on between the PC and modem has little
relationship to what the modems are doing on the link.


John Lundgren - Elec Tech - Info Tech Svcs
Rancho Santiago Community College District
17th St. at Bristol \ Santa Ana, CA 92706
[e-mail]\[e-mail]

------------------------------

From: [e-mail] (Kevin Kadow)
Subject: Re: Chicago 630 Plan - Such As It Is
Organization: Ripco Internet BBS, Chicago
Date: Thu, 9 Feb 1995 08:08:31 GMT


If they really are running out of numbers in the 708 area code, why
not allow people and companies to voluntarily 'give up' their 708
numbers for their choice of 630 numbers?

For example, businesses could release their DID lines, the 2nd ... Xth
lines of hunt groups, or give up a 708 number for a 'vanity' number in
in the new area code.

This would at least have the effect of freeing up enough phone numbers
that new residential lines could remain in the 708 code.


[e-mail]   Kevin Kadow
FREE Usenet/Mail, inexpensive Internet - Ripco... Wearing white hats
since
1983
Dialup:[phone]|Gopher:gopher.ripco.com|Telnet:foley.ripco.com
('info')

------------------------------

From: [e-mail] (Matthew M L CHENG)
Subject: Re: POCSAG to be Upgraded to APOC
Organization: Hong Kong University of Science and Technology
Date: Thu, 9 Feb 1995 13:48:04 +0800


In article <[e-mail]>:

> To everyone interested in POCSAG, and new more advanced terrestrial
> paging systems for communications in tommorrow's world:

> An overview of APOC, the upgrade to POCSAG, is now available by
EMail.
> If you are interested, please send a request to me
([e-mail].
> philips.nl) stating the reasons for your interest.

I would like the overview of APOC. I am now pursuing a research
postgraduate degree in The Hong Kong University of Science and
Technology in the area of wireless communications and so anything in
this area such as paging, cellular radio and PCS is in my interest.
However, I have tried the email address twice to request for the
overview but all the emails are bounced back. Would the original
author kindly send the overview to me by email? My email address is:
[e-mail].


Thanks very much in advance.

Matthew Cheng   Wireless Communications Research Group  HKUST

------------------------------

Date: Thu, 9 Feb 95 11:05:38 EST
From: Carl Moore <[e-mail]>
Subject: Re: Ten Digit Dialing


Usually, the same three-digit combination has NOT been used as both a
prefix and an area code (that one or a nearby one).  Therefore, an
area
code given in a telephone number in, say, spoken form in an
advertisement
can be recognized by the listener as such.  Such courtesy became
"legal"
in the Washington DC area (area codes 202,301,703) and along the
301/410
border in Maryland; in those places, local calls to another area code
are published as NPA +7D (can omit the leading 1, but you may include
it).

Someone told me of having to use leading 1 on local call from Delaware

·
County, PA (possibly 610-485) to Philadelphia.

There are some exceptions to the above-stated use of area codes as
prefixes: I believe it is 909 which is used as a prefix somewhere in
southern California.  And I sent a 312-630 prefix to the Digest
recently.

------------------------------

From: [e-mail] (Mike Roche)
Subject: Re: Unit to "Speak" CLID
Date: 9 Feb 1995 16:24:16 GMT
Organization: Tadpole Technology, Inc. Austin, TX
Reply-To: [e-mail]


Voice Powered Technology has a phone (Tel-It Phone I believe) which
holds 40 recorded names. Each name can have up to three numbers (home,
work etc). It will replay the recorded name between rings if the
number received via CID matches one of the stored numbers. The
recorded numbers can be dialed using voice recognition also (fair
accuracy, names are divided into two groups of 20 which you have to
tell it by pushing a button, up to two speakers with seperate memories
for the voice recognition ... this doesn't mean you can store 80
"names".)  Also has an Name and number CID with a one line LCD Display
and call timer, on-hook dialing (NOT a speakerphone! only mike is in
the handset).  A good value IMHO at $129.95. I bought two and a friend
got one after seeing mine. Available through Sharper Image etc. Also
available direct although I've found VPT diffficult to deal with
directly (bad delivery times and they initially quoted a higher price
when it came out, terrible order line people, customer support poor
and excellant in two calls. I own a Voice Organizer also.)  I wanted
the phones for the CID recital function.

Nits:

-Display bezel makes reading the upper edge of the display very
difficult at
most angles;

-When the voice recognition feature is used, it will replay the
recorded
entry it thinks you said before dialing (good), but if it's wrong you
have to hang up and retry (bad!!!). I wish it would recognize a spoken
"NO" and "guess again" the way the Voice Organizer does.  (Feedback
for the VPT lurkers who I once promised some opinions to after they
responded to an earlier post.)


Mike   [e-mail]

------------------------------

From: Martin McCormick <[e-mail]>
Subject: Re: Clock Slips Again
Date: 8 Feb 1995 16:27:31 GMT
Organization: Oklahoma State University  Stillwater, OK


In article <[e-mail]> [e-mail]
writes:

> If you believe the clock slips are in the LEC's internal network
> then attack it as a quality issue that they must resolve.

 Several people have suggested the method of using a modem with
error-correction turned off to find clock slips.  I have been trying
this and determined that the problem is still there but is very small
compared to what it has been in the past.  The lines leading from the
campus to Southwestern Bell are analog and there is some question
about
what they connect to after leaving the campus.  There are definitely
no
T1's between here and there.

 What we will probably do is wait until we get another trunk
that is really bad and keep it seized until it can be identified.
This will make it easier to point it out to all concerned and maybe
eventually lead to procedures to automatically watch for the problem
before customers tell us about it.

 Many thanks to everybody who has sent past discussions of the
problem or suggestions on how to identify or solve it.


Martin McCormick WB5AGZ   Stillwater, OK
OSU Center for Computing and Information Services Data Communications
Group

------------------------------

From: [e-mail] (Al Gharakhanian)
Subject: Looking For Hands on Networking Experience
Date: 9 Feb 1995 10:52:08 GMT
Organization: Netcom


I have a significant amount of product development experience in the
field of FDDI, ATM, SMDS, LAN and T1/T3 networking.  I am looking for
a way to gain some hands on network design and implementation
experience in an IS or Systems Integration environment.

I would be willing to dedicate a portion of my time (free of charge)
to work toward this goal.

Does anyone have any recommendation?


Thanks.

------------------------------

Organization: Penn State University
Date: Thu, 9 Feb 1995 10:42:14 EST
From: Peter M. Weiss <[e-mail]>
Subject: Re: Who Belongs to 10732 Five-Digit Access Code?


10-732 is also used for AT&T-customer' employee "deals" E.g. PSU has a
True PSU (sm?) deal with AT&T.  Similar but not the same as True USA
(sm).  The only time you need to dial 10-732 is when you want to call
intra-LATA (from your home phone), otherwise it is your PIC.

Billing is NOT handled by the LEC.


[e-mail]

------------------------------

From: [e-mail] (John Mark)
Subject: Re: GTE PCS/Global Roam
Organization: Third Millennium Industries
Date: Wed, 8 Feb 1995 23:44:50 GMT


CO/NY has already launched a similar service (January 1995). CO/NY
customers get a SIM card (they call it a CellCard) for $49.99/year.
They can then purchase or rent a GSM phone and can roam in 23 GSM
countries. The agreement is with Vodaphone in the UK. Incoming calls
must be routed through the customer's NY cellular number. The cost of
roaming is a flat $2.49/minute for outgoing calls regardless of
destination (local or international) and $2.49/minute + toll from NYC
for incoming calls.

------------------------------

From: [e-mail] (David Buerger)
Subject: Re: Cellular Fraud: How Much of it is Real Money?
Date: 9 Feb 1995 09:11:01 -0500
Organization: The Pipeline


TELECOM Digest Editor noted:

>>  Adam Gaffin correctly mentioned that AT&T's Bell Labs were
connected to
>> the network.

>> Most amusing was Brayall's assertion that people should not have
called
>> that number since it was never listed or advertised.

> [TELECOM Digest Editor's Note: I wonder where Adam has been lately?
We
> used to get some very nice articles from here here once in awhile,
but not
> for a long time now.  PAT]

Adam Gaffin is a reporter for {Network World}.  I believe he's about
to
become more involved with reporting on the Internet.  You can reach
him at
[e-mail].


David J. Buerger            v: [phone]
[e-mail]   f: [phone]
3455 Peachtree Industrial Blvd. Suite 271
Atlanta, GA 30136-2657


[TELECOM Digest Editor's Note: I wish he would stay in touch with us
more
often. His reports were always quite good.   PAT]

------------------------------

End of TELECOM Digest V15 #89
*****************************